A tentative contract agreement between Metro and one of its labor unions means some Oregon Zoo employees will begin to pay for parking.

But another employee union is still holding out—saying the government is gouging them by making them pay to park at their jobs.

The American Federation of State, County and Municipal Employees Local 3580 reached a tentative agreement on July 17 with regional planning agency Metro.

The deal, obtained by WW, includes a 2.8 percent cost-of-living pay raise. Union members will vote on the contract next month.

The contract also says AFSCME Local 3580 employees—who include security guards—will pay $40 a month for parking at the zoo. That charge could leap to $80 a month by July 2016.

That's too steep for the Laborers' International Union of North America Local 483, which represents Oregon Zoo employees who take tickets, pick up trash and work the concession stands.

"We've already agreed to increase workers' cost on health care, so all we're asking is that people don't have to take on that additional cost just to do their jobs," union business manager Erica Askin told WW earlier this month.

Local 483 workers have launched a PR campaign that includes handing out stickers to zoo patrons, calling it Zoolidarity.

Representatives from the unions and Metro did not immediately respond to WW's requests for comment.